Bloqueos Nerviosos. Bases Anatómicas del Dolor Somático Abdomino-Pélvico / Nerve Blocks. Anatomy of the Somatic Innervation of the Abdomino-Pelvic Cavity

El dolor abdominal es una de las sintomatologías que afectan con frecuencia la cavidad abdomino-pélvica. Dicha cavidad posee una inervación somática en la que intervienen del séptimo a doceavo nervios intercostales, ramos colaterales y terminales del plexo lumbar y el nervio pudendo; siendo objetivo de este trabajo la descripción anatómica del dolor abdominopélvico a través del plexo lumbar, nervios intercostales y nervio pudendo, sus diferentes patrones y variaciones de conformación, y las implicancias de éstas últimas en las distintas maniobras clínico-quirúrgicas. Se realizó un estudio descriptivo, observacional y morfométrico de la inervación somática de la cavidad abdomino-pélvica, en 50 preparaciones cadavéricas, fijadas en solución de formaldehído, de la Tercera Cátedra de Anatomía, Facultad de Medicina, Universidad de Buenos Aires, entre Agosto/2017-Diciembre/2019. La descripción clásica del plexo lumbar se encontró en 35 casos; la presencia del nervio femoral accesorio en ningún caso; así como también la ausencia del nervio iliohipogástrico en ningún caso; el nervio obturador accesorio se halló en 2 casos; el nervio genitofemoral dividiéndose dentro de la masa muscular del psoas mayor en 6 casos; el nervio cutáneo femoral lateral emergiendo únicamente de la segunda raíz lumbar en 6 casos y por último se encontró la presencia de un ramo del nervio obturador uniéndose al tronco lumbosacro en un caso. Los nervios intercostales y el nervio pudendo presentaron una disposición clásica en todos los casos analizados. Es esencial un adecuado conocimiento y descripción del plexo lumbar, nervios intercostales y nervio pudendo para un adecuado abordaje de la cavidad abdomino-pélvica en los bloqueos nerviosos.

SUMMARY: Abdominal pain is one of the symptoms that affect the abdominal-pelvic cavity. The abdominal-pelvic cavity has a somatic innervation involving the seventh to twelfth intercostal nerves, collateral and terminal branches of the lumbar plexus and the pudendal nerve. The objective of this work is the description of the lumbar plexus, intercostal nerves and pudendal nerve, its different patterns and structure variations, as well as its implications during pain management in patients. A descriptive, observational, and morphometric study of patterns and structure variations of the lumbar plexus, intercostal nerves and pudendal nerve was conducted in 50 formalin-fixed cadaveric dissections of the Third Chair of Anatomy at the School of Medicine in the Universidad de Buenos Aires from August 2017 to December/2019. The standard description of the lumbar plexus was found in 35 cases; accessory femoral nerve was not present in any of the cases; absence of the iliohipogastric nerve was also not found in any case, while the accessory obturating nerve was found in 2 cases; genitofemoral nerve dividing within the muscle mass of psoas in 6 cases; lateral femoral cutaneous nerve emerging only from the second lumbar root in 6 cases and finally, presence of a branch of the obturating nerve was found joining the lumbosacral trunk in one case. The pudendal and intercostal nerve patterns presented a typical pathway in all cases. Adequate knowledge and description of the lumbar plexus, intercostal nerves and pudendal nerve is essential for an adequate approach of the abdominal-pelvic cavity in nerve blocks.

Anatomical variation of the sympathetic trunk and aberrant rami communicantes and their clinical implications.

Surgical interventions involving the sympathetic trunk are increasingly performed to alleviate symptoms of several disorders such as hyperhidrosis. Anatomical variation has been highlighted as one of the main causes behind surgical failure and symptoms recurrence following surgeries conducted on the chain or its surroundings. This study therefore aimed to record anatomical variants within spinal segments C8-T10 of the sympathetic trunk. Thirty Thiel-embalmed cadavers were investigated bilaterally. The stellate ganglion was recorded on 29 sides. Its size was significantly greater in males and on the right side when the coalescence extended to the subsequent ganglion. The intrathoracic nerve of Kuntz was observed on 21 sides and was significantly more prevalent in males. There was a significant positive association between the presence of this nerve and the descending ramus in the first intercostal space. Aberrant rami found between spinal root C8 and the ventral ramus of the first intercostal nerve were introduced as rami communicantes superi. Aberrant rami communicantes were recorded 50 times in total, of which 70% were found in males. Descending rami showed the highest prevalence in upper intercostal levels, especially in males within the first intercostal space. Aberrant neuronal pathways in upper levels were significantly more prevalent when the stellate ganglion was present. The scientific literature has proven to be stochastic as results were significantly higher in past studies in regard to some sympathetic variants. Anatomical findings of the current study as well as the inconsistency of previous data should be acknowledged and considered for better surgical planning.

Anatomical variations of intercostobrachial nerve: A potential candidate for neurotization after traumatic median nerve injury?

BACKGROUND: This study focused on the anatomical characteristics and variations of intercostobrachial (ICBN) nerve and median nerve to investigate the possible use of ICBN in restoration of sensory damage of hand after traumatic median nerve injury and to evaluate the feasibility of ICBN neurotization to median nerve. METHODS: Variations of ICBN were noted in 16 axillary region dissections of eight cadavers. Measurements for ICBN's suitability in terms of neurotization to brachial plexus were done with millimetric devices. The distance of ICBN to the distal end of the lateral (LCMN) and medial (MCMN) contributions of the median nerve and the diameters of ICBN, LCMN, and MCMN were measured. RESULTS: Fifteen axillary dissections exhibited ICBN, whereas it was absent on the left side of one of the cadavers. The mean diameter of ICBN at its origin was 2.0±0.7 mm and the mean diameter of ICBN at its coaptation point was 3.1±0.9 mm. The mean diameter of the LCMN was 3.9±2.0 mm, the mean diameter of MCMN was 3.5±0.9 mm. The length of ICBN was found to be adequate at both 45 and 90° of shoulder abduction to be extended to both LCMN and MCMN. The diameters of LCMN and MCMN were not significantly correlated with the diameter of ICBN both at origin and at coaptation point (LCMN: p=0.55-0.63 and MCMN: p=0.89-0.85). There is no significant difference between the diameter of LCMN and the diameter of ICBN at its coaptation point (p=0.168) and also between the diameter of MCMN and the diameter of ICBN at its coaptation point (p=0.232). CONCLUSION: All ICBNs dissected showed adequate length to reach the lateral and medial contribution of the median nerve directly. The ICBN could be a feasible candidate since its diameter was close to LCMN and MCMN according to the descriptive and inferential statistics.

An uncommon, unilateral motor variation of the intercostobrachial nerve.

The intercostobrachial nerve (ICBN) is commonly defined as a purely sensory nerve supplying the skin of the lateral chest wall, axilla, and medial arm. However, numerous branching patterns and distributions, including motor, have been reported. This report describes an uncommon variant of the right ICBN observed in both an 86-year-old white female cadaver and a 77-year-old white male cadaver. In both cases the ICBN presented with an additional muscular branch, termed the "medial pectoral branch", piercing and therefore innervating the pectoralis major and minor muscles. Clinically, the ICBN is relevant during surgical access to the axilla and can result in sensory deficits (persistent pain/loss of sensory function) to this region following injury. However, damage to the variation observed in these cadavers may result in additional partial motor loss to pectoralis major and minor.

A Cadaveric Anatomical and Histological Study of Recipient Intercostal Nerve Selection for Sensory Reinnervation in Autologous Breast Reconstruction.

BACKGROUND: Autologous breast reconstruction (ABR) has grown in popularity due to improved aesthetic and long-term patient reported outcomes, but data regarding sensory reinnervation of autologous flaps remain limited. Traditionally, the lateral cutaneous branch of the fourth intercostal nerve has been used for flap neurotization, but the use of the anterior cutaneous branch of the intercostal nerves (ACB) offer a more optimal location to the microsurgical field when using internal mammary vessels for the microanastomosis. This study aimed to evaluate the optimum ACB recipient site level for sensory nerve coaptation in ABR. METHODS: Twelve hemi-chests were dissected from six fresh cadaveric females. Costal cartilages were removed and the anterior cutaneous intercostal nerve (ACB) and the lateral (subcutaneous) division of the anterior cutaneous branch (LACB) of the intercostal nerve were exposed. Anatomical measurements were recorded, and nerve samples were evaluated histologically with carbonic anhydrase staining to differentiate sensory fascicles. Assessment of fascicular diameter, axonal counts, and fascicular area were compared. RESULTS: A total of 75 nerve specimens were assessed. The ACB was identified at all levels (100%) and the subcutaneous LACB was noted consistently in the second to fourth rib space (96% cadavers), with a median length of 43, 37.5, and 37 mm, respectively. Across all rib spaces, the fascicular and axonal counts were comparable between the LACB and ACB. Nerves in the second intercostal space had a significantly larger mean fascicular area mean (112,816 ± 157,120 µm2) compared with that in the fourth (mean 26,474 ± 38,626 µm2), p = 0.03. Axonal count of sensory fascicles was the highest in the second intercostal nerves (p < 0.05). CONCLUSION: This study provides anatomical and histological basis to determine the optimum recipient site choice for sensory coaptation in microsurgical breast reconstruction. This would aid in operative decision-making regarding the ideal recipient anterior cutaneous intercostal nerve branches for recipient site coaptation in ABR.

Anatomical Evaluation of a Conventional Pectoralis II Versus a Subserratus Plane Block for Breast Surgery.

BACKGROUND: Pectoralis I and II (Pecs I/Pecs II) blocks are modern regional anesthetic techniques performed in combination to anesthetize the nerves involved in breast surgery and axillary node dissection. Pecs II spread and clinical efficacy is thought to be independent of whether injection occurs between pectoralis minor and serratus anterior or deep to serratus anterior. Injecting deep to serratus anterior onto the rib may be technically easier; however, our clinical experience suggests that this approach may be less effective for axillary dissection. We undertook a cadaveric study to evaluate a subserratus plane approach for use in breast and axillary surgery. METHODS: Ultrasound-guided blocks using methylene blue dye were performed on 4 Genelyn-embalmed cadavers to assess and compare dye spread after a conventional Pecs II and a subserratus plane block at the third rib. RESULTS: Conventional Pecs II injection demonstrated staining of the intercostobrachial nerve, third intercostal nerve, thoracodorsal nerve, long thoracic nerve, medial pectoral, and lateral pectoral nerve. The subserratus plane produced significantly less axillary spread, incomplete staining of the medial pectoral, and very minimal staining of the lateral pectoral nerve. Dye spread was limited to the lateral cutaneous branches of the intercostal nerves in both injections. CONCLUSIONS: In our cadaveric study, injecting deep to serratus plane produced significantly less axillary spread. For breast surgery excluding the axilla, both techniques may be effective; however, for axillary dissection, the conventional Pecs II is likely to produce superior analgesia and additionally may help achieve complete coverage of the deeper pectoral nerve branches.

BRILMA block for costal cartilage excision: Case report. / Bloqueo BRILMA para extirpación de cartílago costal: caso clínico.

The block of the lateral branches of the intercostal nerves in the middle axillary line (BRILMA) is an interfascial ultrasound-guided block for analgesia in thoracic wall and upper abdominal surgery, presenting as an adequate alternative to neuraxial techniques. We present the case of a 49-year-old female scheduled for idiopathic subglottic stenosis repair with a costal cartilage graft from the 10th rib and tracheotomy. At the end of the surgery, unilateral ultrasound-guided BRILMA block with 20ml of ropivacaine 0.2% was performed at the level of the 6th rib, uneventfully. Postoperatively, the patient referred a maximum level of pain of 3/10. There was no opioid consumption after the 2nd postoperative day, although a subcostal incision may produce considerable pain. BRILMA is a superficial block, easily reproducible in most patients. It diminishes the number of punctures needed in the thoracic wall, as well as the risk for pneumothorax and local anesthetic toxicity.

Study of abdominal wall muscle innervation applied to large-defect closure in congenital diaphragmatic hernia.

In large congenital diaphragmatic hernias (CDHs), direct suture of the diaphragm is impossible. Surgeons can use a triangular internal oblique muscle (IOM) plus transverse abdominis muscle (TAM) flap. Its caudal limit faces the medial extremity of the 11th rib. Clinical studies show that the flap is not hypotonic but that the procedure could expose patients already presenting a hypoplastic lung to external oblique muscle (EOM) hypotonia. The aims of this study were to study EOM innervation by the 10th intercostal nerve (ICN) and ICN innervation to the IOM and TAM. Forty cadaveric abdominal hemi-walls were dissected. The number of branches and the trajectory of each specimen's 10th ICN were studied medially to the medial extremity of the 11th rib (MEK11) using surgical goggles and a microscope (Carl Zeiss®). The 10th ICN was consistently found between the IOM and TAM. There was a median of nine branches from the 10th ICN to the EOM, 77% of them medial to the MEK11. Median values of nine and 12 branches for the IOM and TAM were found, 60% and 51%, respectively, medial to the MEK11. These results argue in favor of good innervation to the IOM plus TAM flap but also indicate postoperative abdominal weakness exposing patients to herniation risks, as more than 75% of the branches from the 10th ICN to the EOM were sectioned or pulled away during flap detachment. Clin. Anat., 33:759-766, 2020. © 2019 Wiley Periodicals, Inc.

Aberrant bifurcation of intercostobrachial nerve in the axilla: A case report.

Intercostobrachial nerve (ICBN) studies have been undertaken by many authors as it is a highly variable structure with numerous patterns reported worldwide. ICBN is a frequently damaged structure in Axillary Lymph Node Dissection (ALND) or mastectomy. Compression of this nerve, due to the enlargement of axillary lymph nodes from cancer breast may be presented as referred pain along the medial side of arm. Different patterns on the course and distribution of the ICBN have been described in literature. We encountered a lesser known variation of the ICBN where it pierced the second intercostal space as a single trunk and immediately divided into two branches. The putative clinical implications of this aberrant bifurcation are of value in significantly diminishing complications such as pain and sensory disturbances presenting after mastectomy and ALND. The findings of the presentation may be of use by surgeons and interventionists in approaching the area in a more precautious manner.

Intercostal nerve block of the anterior cutaneous branches and the sensibility of the female breast.

INTRODUCTION: Better sensation in the reconstructed breast improves the quality of life. Sensory nerve coaptation is a valuable addition to autologous breast reconstruction. There are few publications concerning the sensory nerves of the breast and the nipple-areola complex and reports are contradictory, so it is unknown which nerve is best suited as a recipient for coaptation. The current study serves as a proof of concept. MATERIALS AND METHODS: The areas innervated by the anterior cutaneous branches (ACBs) of the intercostal nerves (ICNs) were studied on two separate occasions in two healthy women. First, the ACBs of ICNs 2-5 were individually blocked using ultrasound. Next, the ACBs of all levels were blocked simultaneously. Sensation was measured using Semmes-Weinstein monofilaments. The numbed areas corresponding to the ICNs were drawn in a raster of 2 × 2 cm. RESULTS: The largest area was supplied by the ACB of the 4th ICN, located in the upper (UIQ) and the lower (LIQ) inner quadrants of the breast. The 2nd-largest area was supplied by the ACB of the 3rd ICN. Blockage of ACBs 2-5 affected sensation in the nipple and the areola. CONCLUSIONS: Blockage of all levels 2-5 partially affected sensation in the nipple-areola complex, suggesting innervation by a nerve plexus consisting of both ACBs and lateral cutaneous branches (LCBs). ACB4 supplied the largest area of the breast in the UIQ and LIQ and could be best suited for sensory nerve coaptation to optimize sensation in the autologously reconstructed breast.

Age and individual anatomical variability of intercostal nerves in human fetuses.

Performing fetal operations on the walls of the thorax and abdomen requires detailed information dealing with the anatomical variability of the intercostal nerves (IN) in human fetuses. Therefore, our study aimed at determining the topographic and anatomical characteristics of the I-XII IN during the period of human ontogenesis. The study involved 70 specimens of fetuses aged 4-10 months, by means of macromicroscopic preparation, superficial staining of dissected vessels and nerves and morphometry. The variability of the topography and asymmetry of the trunks of IN and their branches were revealed. The direction of the lateral musculocutaneous branches of the inferior IN does not coincide with the direction of the muscle bundles of the external abdominal oblique muscle. The branches of the I IN are functionally different, since the superior branch branches out in the skin and vessels, and the inferior one - in the stratum of the internal intercostal muscle. The anterior musculocutaneous branches of the II-VII IN occur in the front of the parasternal neurovascular bundle and are related with each other, with parasternal nerve or with the nerve plexus of the internal thoracic artery. The trunks of adjacent IN relate to one another by means of rare connecting branches, numerous and diverse in shape links are observed between the anterior and lateral musculocutaneous branches of the VIII-XII IN in the area of the anterior-lateral regions of the abdominal wall. The connecting branches descend from the nodes of the thoracic section of the sympathetic trunk to the IN.

Two mammalian species in which the intercostal nerves innervate the serratus anterior or scalenus muscles together with the cervical nerves: an important clue to clarify the homology of cervico-thoracic trunk muscles in mammals.

The levator scapulae, rhomboideus, and serratus anterior muscles (as a group referred to the dorsal shoulder girdle muscles) and the scalenus muscles in mammals are usually innervated by cervical nerves. However, in koalas, the serratus anterior is additionally innervated by the lateral cutaneous branch of the first intercostal nerve. In cats, as in some other mammalian species, a part of the scalenus muscle (scalenus longus muscle) is innervated by the lateral cutaneous branches of the intercostal nerves. A precise comparison of the innervating nerves at the same segment in these two cases could clarify the homological relationship between the cervical and thoracic trunk muscles. In this context, the aim of this study was to follow the nerve fibers included in the nerves supplying the dorsal shoulder girdle and scalenus muscles up to the level of the spinal nerve roots in two koalas and two cats. The resultant observations revealed that both of the nerves to the serratus anterior in koalas and to the scalenus muscles in cats from the lateral cutaneous branch of the intercostal nerve occupy the same position in the spinal roots as the cervical nerve branches to the dorsal shoulder girdle muscles and the thoracic nerve branches to the external intercostal muscle. Based on these results, the axial trunk muscles in the cervico-thoracic region could be classified as follows: the scalenus and dorsal shoulder girdle muscles belong to the same lateral axial trunk muscle group as the external intercostal muscle, and are clearly distinguished from the medial group, such as the internal and innermost intercostal muscle.

Predictable Location of Breast Sensory Nerves for Breast Reinnervation.

The sensory innervation to the breast originates from the medial and lateral cutaneous branches of the third to fifth intercostal nerves, which are at risk for injury or loss during mastectomy. Providing reinnervation after mastectomy was introduced almost 20 years ago, but it is not widely performed, perhaps because of the difficulty of locating a recipient nerve. The authors have performed cadaveric dissections to allow for precise anatomical localization of the lateral intercostal branch providing breast sensation. Bilateral chest dissections were performed on 10 female cadavers. The lateral intercostal nerve providing sensation to breast tissue was identified. The distances from the sternum, the midclavicular line, and the lateral pectoralis minor-in addition to nerve diameter-were measured. The nerve was successfully identified bilaterally in all cadavers. The majority of nerves (16 of 20) exited from under the fourth rib. The average distance from the sternum was 13.1 ± 1.3 cm (range, 10 to 15 cm) and the average distance from the midclavicular line was 11.8 ± 2.2 cm (range, 8 to 16 cm). The nerve exited at the lateral border of the pectoralis minor or within 2 cm from the lateral border for all cadavers. The diameter of the nerve was consistently 2 mm. The nerve traveled under the thoracodorsal vessels, aiding in identification. The authors identified the predictable location of the lateral intercostal nerve providing sensation to the breast. The authors hope that by enabling surgeons to locate this nerve, more well-conducted studies will be performed investigating techniques and outcomes for breast reinnervation.

Peripheral neuropathic mimics of visceral abdominal pain: Can physical examination limit diagnostic testing?

BACKGROUND: The emergency department evaluation of patients with abdominal pain is most appropriately directed at identifying acute inflammation, infection, obstruction, or surgical disease. Doing so commonly involves "routine" (and often extensive) diagnostic imaging and laboratory testing. Benign mimics of serious visceral abdominal pain that can be diagnosed by physical exam and confirmed with local anesthetic injections have been identified over the last century. These syndromes derive from painful irritation of the intercostal nerves by a mobile rib below, or from impingement of the cutaneous branches of those same intercostal nerves as they penetrate the abdominal wall. These peripheral neuropathic mimics of visceral abdominal pain continue to go unrecognized and underdiagnosed. METHODS: Our purpose is to review the affirmative diagnosis of non-visceral abdominal pain by physical examination. RESULTS: The consequences of failure to identify these conditions are considerable. In the search for a diagnosis that is literally at the provider's fingertips, patients frequently undergo months to years of fruitless and often invasive diagnostic tests, not uncommonly including unsuccessful surgeries. CONCLUSIONS: With proper consideration of and appropriate testing for visceral etiologies, a carefully directed physical examination may yield an affirmative diagnosis in a percentage of these common emergency department patients.

Topographical study of the connections of the rami communicantes from the first to the fifth thoracic sympathetic ganglia.

This study investigated the morphological variations and histological patterns of the rami communicantes (RCs) arising from the first to the fifth thoracic sympathetic ganglia, and considered the clinical significance of these variations. Fifty upper thoracic portions from 26 adult Korean cadavers were used in this study. There were 731 RCs arising from the first to the fifth thoracic sympathetic ganglia. They were classified into three types depending on the connection between the sympathetic ganglion and the intercostal nerves: in type I, the RCs connected the ganglion to the corresponding intercostal nerve, and in types II and III, respectively, they connected it to the nerve one level above or below the corresponding intercostal nerve. Some RCs of types I and II could not be observed without additional preliminary surgical procedures. Diverse combinations of RC types arose from the first to the fifth thoracic sympathetic ganglia, combinations of types I and III being the most common (70%) in the first sympathetic ganglion and those comprising only type I being most frequent in the other ganglia. The RCs could not be identified by the naked eye in either fresh or fixed cadavers, so they were confirmed on the basis of their histological appearance. These results are expected to improve knowledge of morphological variations of the RCs in the upper five thoracic sympathetic ganglia, and to provide helpful information for clinical management in this region. Clin. Anat. 31:1151-1157, 2018. © 2018 Wiley Periodicals, Inc.

Anterior cutaneous nerve entrapment syndrome (ACNES).

The abdominal wall is frequently overlooked as a potential source of chronic abdominal pain. In anterior cutaneous nerve entrapment syndrome (ACNES), irritated intercostal nerves cause severe abdominal pain. Current textbooks fail to acknowledge ACNES. Aim of the present review is to provide detailed information on patient history, physical examination, and a three-step treatment protocol including abdominal wall injections and a localized removal of terminal branches of intercostal nerves.

The Functional Anatomy of Nerves Innervating the Ventral Grooved Blubber of Fin Whales (Balaenoptera Physalus).

Nerves that supply the floor of the oral cavity in rorqual whales are extensible to accommodate the dramatic changes in tissue dimensions that occur during "lunge feeding" in this group. We report here that the large nerves innervating the muscle component of the ventral grooved blubber (VGB) in fin whales are branches of cranial nerve VII (facial nerve). Therefore, the muscles of the VGB are homologous to second branchial arch derived muscles, which in humans include the muscles of "facial expression." We speculate, based on the presence of numerous foramina on the dorsolateral surface of the mandibular bones, that general sensation from the VGB likely is carried by branches of the mandibular division (V3) of cranial nerve V (trigeminal nerve), and that these small branches travel in the lipid-rich layer directly underlying the skin. We show that intercostal and phrenic nerves, which are not extensible, have a different wall and nerve core morphology than the large VGB nerves that are branches of VII. Although these VGB nerves are known to have two levels of waviness, the intercostal and phrenic nerves have only one in which the nerve fascicles in the nerve core are moderately wavy. In addition, the VGB nerves have inner and outer parts to their walls with numerous large elastin fibers in the outer part, whereas intercostal and phrenic nerves have single walls formed predominantly of collagen. Our results illustrate that overall nerve morphology depends greatly on location and the forces to which the structures are exposed. Anat Rec, 300:1963-1972, 2017. © 2017 Wiley Periodicals, Inc.